BFF's parents splitting up, what can i say/do to make her feel better??

Okay, my best friend's parents have been together almost 25 years, and have her (15) and her little sister (11) together. Her dad travels a lot for work and is only home a few days a week. I stay at their house a lot, and they seemed like they were doing great, her dad is really funny and nice to everybody. A couple days ago he told them that he's leaving them for a younger married lady with 3 small children he met a few months ago, whom he apparently loves much more than his family. He's still staying with them for a while in the guest room until his "girlfriend" separates from her husband. My friend is devastated obviously, and i have no idea what to say to her, and i feel awful. All i really know to do is listen to her vent and give hugs and chocolate. My mom died last year and she was there for me all the time, and always knew the right things to say and do to make me feel better. Every time she has to tell someone they broke up, she starts crying again. She's like swimming in awkwardness at her house by herself, everybody's upset except her dad, who's always acting like nothing's wrong or fighting. I'm pretty pissed at him. We can't be at each other's house all the time obviously, and neither of us can drive alone yet so i can't really go "rescue" her for shopping or a movie or anything because one of our parents would have to be there, which is awkward too.
Does anyone have any ideas about what i could say or do to cheer her up? I'm desperate here, any advice would be greatly appreciated :)